log.bshell is filled with error messages like the one below...

No definition in definition file for fil_pathname(F_ADDF:btfacpeuro_sign.gif, btfacpeuro_sign.gif)

How can we eliminate these messages from getting logged in log.bshell?

Note: All icons exist under $BSE/gif/gfd0002

GIFs/Icons in LN are stored as Additional Files. Scan them in the corresponding package-module-vrc combination and migrate them across environments.

More info in help:

Additional Files (ttadv2570m000)
Use this session to view and maintain additional files.
Note
From SSA ERP Tools 6.0a on, additional files are stored in a specific package, module, and package VRC, which are displayed in the fields of the current session.
If you delete a record, the additional file is also physically deleted from the system.
To insert a whole range of additional files, use the Import Additional Files (ttadv2270m000) session, to which you can zoom through the Specific menu.